<template>
  <div class="xtx-pagination">
    <a @click="changePage(myCurrentPage-1)" href="javascript:;" v-if="myCurrentPage > 1">上一页</a>
    <a href="javascript:;" v-else class="disabled">上一页</a>

    <span v-if="pager.start> 1">...</span>
    <a @click="changePage(i)"  href="javascript:;" :class="{active:i==myCurrentPage}" v-for="i in pager.btnArr" :key="i">{{i}}</a>

    <span v-if="pager.end < pager.pageCount">...</span>
    <a @click="changePage(myCurrentPage+1)"  href="javascript:;" v-if="myCurrentPage<pager.pageCount">下一页</a>
    <a  href="javascript:;" v-else class="disabled">下一页</a>

  </div>
</template>
<script>
import { computed, ref, watch } from 'vue'
export default {
  name: 'XtxPagination',
  props: {
    total: {
      type: Number,
      default: 100
    },
    pageSize: {
      type: Number,
      default: 10
    },
    currentPage: {
      type: Number,
      default: 1
    }
  },
  setup (props, { emit }) {
    // 需要数据
    const count = 5
    const myCurrentPage = ref(1)
    // 总页数
    const myTotal = ref(100)

    const myPageSize = ref(10)
    // 其他数据
    const pager = computed(() => {
      // 总页数
      const pageCount = Math.ceil(myTotal.value / myPageSize.value)

      const offset = Math.floor(count / 2)
      let start = myCurrentPage.value - offset
      let end = start + count - 1

      if (start < 1) {
        start = 1
        end = start + count - 1 > pageCount ? pageCount : start + count - 1
      }

      if (end > pageCount) {
        end = pageCount
        start = end - count + 1 < 1 ? 1 : end - count + 1
      }
      const btnArr = []
      for (let i = start; i <= end; i++) {
        btnArr.push(i)
      }
      return {
        pageCount,
        btnArr,
        start,
        end
      }
    })
    // 监听props的变化
    watch(props, () => {
      myTotal.value = props.total
      myPageSize.value = props.pageSize
      myCurrentPage.value = props.currentPage
    }, { immediate: true })

    // 切换分页
    const changePage = (page) => {
      myCurrentPage.value = page

      emit('current-page', page)
    }

    return {
      myCurrentPage,
      pager,
      changePage
    }
  }
}
</script>
<style scoped lang="less">
.xtx-pagination {
  display: flex;
  justify-content: center;
  padding: 30px;
  > a {
    display: inline-block;
    padding: 5px 10px;
    border: 1px solid #e4e4e4;
    border-radius: 4px;
    margin-right: 10px;
    &:hover {
      color: @xtxColor;
    }
    &.active {
      background: @xtxColor;
      color: #fff;
      border-color: @xtxColor;
    }
    &.disabled {
      cursor: not-allowed;
      opacity: 0.4;
      &:hover {
        color: #333;
      }
    }
  }
  > span {
    margin-right: 10px;
  }
}
</style>
